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[YesAuto Technical Interpretation] When mentioning joint venture hybrid models in China, many of my friends will definitely think of the hybrid Camry for the first time. However, the domestically produced hybrid model of Dongfeng Nissan’s new Loulan hybrid model has changed the hybrid system from a single company. There are two flowers and one branch each. Toyota's hybrid system represents a conventional approach, while the hybrid system of Dongfeng Nissan New Loulan represents another unconventional approach. So what is the difference between this unconventional hybrid system? Let's take a look together.

Why use a supercharged engine?

This engine was specially developed by Nissan in 2011 for HEV models (ie hybrid models). Its engine model is QR25DER. This engine does not use the popular turbocharged engines on the market, nor does it use direct injection technology. See At this point, everyone will definitely have questions, why did Nissan go against the trend?

Nissan’s engine experts said that during their investigation, they found that in actual use, there are more low-speed and high-load usage conditions, and this kind of working condition is turbocharging’s worst job, but it is precisely the mechanical increase. The place where the pressure energy exerts the greatest efficiency (that is, the low-speed torque is large). If turbocharging is not used, then direct injection is not so necessary. In fact, turbocharging and direct injection are two inseparable elements when solving the exhaust gas problem. The turbocharger has a lot of heat capacity in the turbine housing. After the start-up, this part will absorb part of the exhaust heat, so that the catalyst in the three-way catalytic converter cannot quickly reach the operating temperature, so that the exhaust emissions will be more serious after the start-up. With direct injection, the injection time can be changed so that unburned HC compounds remain in the exhaust gas. In this way, the exhaust emissions can be up to standard by heating the catalyst.

However, Nissan’s engineers believe that there is no such problem when using supercharged. The exhaust system of this engine is the same as the non-supercharged QR25DE. The catalyst is placed immediately behind the exhaust manifold so that the catalyst is It can be heated quickly. It solves the problem that the catalyst quickly reaches the working temperature, so there is no need to use direct injection, and the use of manifold injection can also reduce problems such as carbon deposits.

Of course, in addition to emissions and daily operating conditions, Nissan finally decided to adopt supercharger from the cost, installation method, efficiency, and power. After discussion, they believe that turbocharging is only superior in terms of power. In other respects, the two are almost the same or the supercharger is better than the turbocharger, because the current form of engine supercharging is finally determined.

What are the technical highlights of this engine?

Although the engine model is only one letter behind the 2.5L naturally aspirated engine, this supercharged engine is very different in some details, such as the integrated water cooling system, which is specially matched for HEV models. The frequency converter of the electric motor in the HEV system will generate a lot of heat when it is working. To ensure the normal operation of the frequency converter, Nissan integrates the cooling system of the engine with the heat dissipation system of the frequency converter, and the water cooling system of the engine is used to ensure that The normal operation of the inverter.

In addition, it also uses an electronically controlled active suspension system to reduce engine vibration. As for the continuously variable valve lift system, piston DLC coating and other technologies are all used on this engine.

Electric motor + two sets of clutches and batteries

The electric motor used in the new Loulan hybrid system has a maximum power of 15kW (20 horsepower) and a maximum torque of 160N·m. It is cleverly arranged between the engine and the gearbox. At the same time, it is matched with the CVT 8 specially provided by JATCO for hybrid models. The Hybird gearbox makes it possible to ensure that the volume of the entire system is the same as that of a non-supercharged engine even when an electric motor is added.

As mentioned above, the electric motor is located between the engine and the gearbox, and in order to accurately ensure the operation of the system, a set of clutches are designed on both sides of the electric motor for control. It should be specially explained here that the clutch between the electric motor and the engine is The dry multi-plate clutch is locked when the electric motor is working, and disconnected when the engine is working; the clutch between the electric motor and the gearbox is a wet clutch, which functions similarly to the torque converter of a normal gearbox, and is responsible for power transmission Separation and locking.

Regarding the battery, the battery capacity of this car is only 0.6kWh, which is composed of 40 lithium batteries. Seeing this, I believe everyone will realize that such a small battery capacity cannot support a car for long-distance driving with pure electricity. . Nissan’s engineers are also very frank. This hybrid system is different from the traditional hybrid. Its significance lies in assisting driving. As for how to assist, the following article will explain in detail.

Does this system take up space?

From the current point of view, because the battery pack of this system is set in the position of the central armrest box, the storage space of the central armrest is relatively greatly affected.

Why does the Infiniti QX60 Hybird with the same hybrid system put the battery in the lower part of the back seat? New Loulan did not adopt such a design? Nissan’s engineers said that the design of the QX60 Hybird central armrest box cannot accommodate a battery pack composed of 40 lithium batteries, while the new Loulan’s is possible, and the placement of the new Loulan at the central armrest box can also save part of the high voltage of the hybrid system. The cost of wires.

In addition to this system, are there any other options?

Friends who are familiar with Nissan’s hybrid system should know. In fact, the hybrid system used on Nissan’s CIMA, FUGA and Infiniti Q50/Q70L is different from that of the new Loulan. The three cars mentioned above are used It is a set of hybrid system based on FR (engine longitudinal front rear drive), and the entire hybrid system is also composed of 3.5L VQ35HR engine + 67 horsepower electric motor. The battery is 1.3kWh lithium ion battery provided by Hitachi. This allows it to travel 2 kilometers on pure electricity when it is fully charged.

Details of Nissan's existing hybrid system
Use model Infiniti Q70/Q50 Infiniti QX60/Xin Loulan Xinqijun
Drive form FR (engine longitudinal rear drive) FF (engine horizontal front front drive)
engine VQ35HR
inhale naturally
QR25DER
Supercharged
MR20DD
In-cylinder direct injection
Motor Power 50kW (67 horsepower) 15kW (20 horsepower) 30kW (40 horsepower)
Number of battery packs 96 lithium-ion batteries 40 lithium-ion batteries 56 lithium-ion batteries
Battery pack capacity 1.3kWh 0.6kWh 0.9kWh

In addition, Nissan also has a hybrid system similar to the new Loulan hybrid version, that is, the hybrid system in the form of FF (engine front front drive) that is currently equipped with the overseas version of the new Qijun. The system is composed of a 2.0L MR20DD engine + 40 horsepower electric motor, and its battery capacity is 0.9kWh. Similarly, this system cannot provide pure electricity to drive the vehicle.

In addition to the above two systems, Nissan’s third hybrid system is the one currently used in the new Loulan and Infiniti QX60. After a comprehensive analysis by the manufacturer, the FR hybrid requires a 3.5L V6 engine with such a displacement. In many countries, it will face high taxes and fees, which will affect sales; while the FF format such as Qijun will face The power cannot meet the low-torque requirements, so Nissan finally chose a hybrid system with a 2.5L supercharged engine and a 20-horsepower electric motor for the new Loulan. This not only ensures the power requirements, but also reduces fuel consumption through the hybrid system. .

Analysis of working status of hybrid system

As mentioned above, the electric motor part of the new Loulan hybrid system was originally designed to assist the vehicle in driving, so how does it assist?

When the vehicle is started, the clutch between the electric motor and the gearbox is locked first, and the vehicle is driven by the electric motor. Then the clutch between the engine and the electric motor is also immediately locked, allowing the power of the engine to continue to drive the vehicle forward. The clutch between the gearboxes is first disengaged. This design can reduce fuel consumption in the starting phase.

In the rapid acceleration phase, the two sets of clutches are all locked, and the electric motor and engine are involved in the work. At this time, the vehicle's dynamic response is faster.

In the cruise phase, both sets of clutches are locked at the same time. At this time, the power source of the vehicle is the engine, and the electric motor turns into a generator to charge the lithium battery.

In the deceleration phase, the clutch between the motor and the engine is disengaged, and the motor becomes a generator to convert kinetic energy into electrical energy and store it in the battery. In addition, energy recovery can also help the vehicle decelerate and reduce the loss of vehicle brake pads.

Through working under the above four different working conditions, the official comprehensive fuel consumption of the new Loulan hybrid power system is 8.2L/100km, while the comprehensive fuel consumption of the new Loulan with the same displacement 2.5L naturally aspirated model is 9.0L/100km , In comparison, the fuel consumption of the hybrid version is about 10% lower.

Does it affect handling and driving?

When it comes to hybrid models, we have to mention their driving and handling feeling. For example, some hybrid models have large and heavy battery packs, which makes them somewhat different in handling and driving. As expected, this hybrid system of New Loulan uses the lightest and thinnest lithium battery developed by Hitachi, and the weight of the entire battery system is only about 30kg. This weight is completely negligible on a family car, so it provides better The handling and driving performance can also have lower fuel consumption, why not?

to sum up:

Assisted driving is the greatest significance of the new Loulan hybrid power system. Although it cannot be driven by pure electric vehicles alone like the traditional hybrid power system, it can also ensure good driving and operation while reducing fuel consumption. I feel that it is attractive from the point of view.

Favor the Atkinson cycle and talk about Lexus hybrid technology
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